diff --git a/Arduino.mk b/Arduino.mk
index d245c36..a238fe6 100644
--- a/Arduino.mk
+++ b/Arduino.mk
@@ -261,7 +261,9 @@ else
 endif
 
 # include Common.mk now we know where it is
-include $(ARDMK_DIR)/Common.mk
+ifndef COMMON_INCLUDED
+    include $(ARDMK_DIR)/Common.mk
+endif
 
 # show_config_variable macro is available now. So let's print config details for ARDMK_DIR
 ifndef ARDMK_DIR_MSG
@@ -317,18 +319,19 @@ else
     ifeq ($(ARCHITECTURE),avr)
         ARDUINO_ARCH_FLAG = -DARDUINO_ARCH_AVR
     else
-        ifeq ($(ARCHITECTURE),sam)
-            ARDUINO_ARCH_FLAG = -DARDUINO_ARCH_SAM
-        else
-            ARDUINO_ARCH_FLAG = -DARDUINO_ARCH_$(shell echo $(ARCHITECTURE) | tr '[:lower:]' '[:upper:]')
-        endif
+        ARDUINO_ARCH_FLAG = -DARDUINO_ARCH_$(shell echo $(ARCHITECTURE) | tr '[:lower:]' '[:upper:]')
     endif
 endif
 
 ########################################################################
 # 1.5.x vendor - defaults to arduino
 ifndef ARDMK_VENDOR
-	ARDMK_VENDOR = arduino
+    ARCH_LINUX := $(shell grep "Arch Linux" /etc/os-release 2>/dev/null)
+    ifdef ARCH_LINUX
+        ARDMK_VENDOR = archlinux-arduino
+    else
+        ARDMK_VENDOR = arduino
+    endif
     $(call show_config_variable,ARDMK_VENDOR,[DEFAULT])
 else
     $(call show_config_variable,ARDMK_VENDOR,[USER])
@@ -454,7 +457,14 @@ ifndef AVR_TOOLS_DIR
             AVR_TOOLS_DIR = $(SYSTEMPATH_AVR_TOOLS_DIR)
             $(call show_config_variable,AVR_TOOLS_DIR,[AUTODETECTED],(found in $$PATH))
         else
-            echo $(error No AVR tools directory found)
+            # One last attempt using avr-gcc in case using arm
+            SYSTEMPATH_AVR_TOOLS_DIR := $(call dir_if_exists,$(abspath $(dir $(shell which $(avr-gcc)))/..))
+            ifdef SYSTEMPATH_AVR_TOOLS_DIR
+                AVR_TOOLS_DIR = $(SYSTEMPATH_AVR_TOOLS_DIR)
+                $(call show_config_variable,AVR_TOOLS_DIR,[AUTODETECTED],(found in $$PATH))
+            else
+                echo $(error No AVR tools directory found)
+            endif
         endif # SYSTEMPATH_AVR_TOOLS_DIR
 
     endif # BUNDLED_AVR_TOOLS_DIR
@@ -644,6 +654,9 @@ ifeq ($(strip $(NO_CORE)),)
                 USB_PID := $(call PARSE_BOARD,$(BOARD_TAG),menu.(chip|cpu).$(BOARD_SUB).build.pid)
             endif
         endif
+
+        # add caterina flag to ARD_RESET_OPTS
+        ARD_RESET_OPTS += --caterina
     endif
 
     # normal programming info
@@ -745,34 +758,21 @@ endif
 # Reset
 
 ifndef RESET_CMD
-	ARD_RESET_ARDUINO := $(shell which ard-reset-arduino 2> /dev/null)
-	ifndef ARD_RESET_ARDUINO
-		# same level as *.mk in bin directory when checked out from git
-		# or in $PATH when packaged
-		ARD_RESET_ARDUINO = $(ARDMK_DIR)/bin/ard-reset-arduino
-	endif
-    ifneq ($(CATERINA),)
-        ifneq (,$(findstring CYGWIN,$(shell uname -s)))
-          # confirm user is using default cygwin unix Python (which uses ttySx) and not Windows Python (which uses COMx)
-          ifeq ($(shell which python),/usr/bin/python)
-            RESET_CMD = $(ARD_RESET_ARDUINO) --caterina $(ARD_RESET_OPTS) $(DEVICE_PATH)
-          else
-            RESET_CMD = $(ARD_RESET_ARDUINO) --caterina $(ARD_RESET_OPTS) $(call get_monitor_port)
-          endif
-        else
-            RESET_CMD = $(ARD_RESET_ARDUINO) --caterina $(ARD_RESET_OPTS) $(call get_monitor_port)
-        endif
+  ARD_RESET_ARDUINO := $(shell which ard-reset-arduino 2> /dev/null)
+  ifndef ARD_RESET_ARDUINO
+    # same level as *.mk in bin directory when checked out from git
+    # or in $PATH when packaged
+    ARD_RESET_ARDUINO = $(ARDMK_DIR)/bin/ard-reset-arduino
+  endif
+  ifneq (,$(findstring CYGWIN,$(shell uname -s)))
+      # confirm user is using default cygwin unix Python (which uses ttySx) and not Windows Python (which uses COMx)
+      ifeq ($(shell which python),/usr/bin/python)
+        RESET_CMD = $(ARD_RESET_ARDUINO) $(ARD_RESET_OPTS) $(DEVICE_PATH)
+      else
+        RESET_CMD = $(ARD_RESET_ARDUINO) $(ARD_RESET_OPTS) $(call get_monitor_port)
+      endif
     else
-        ifneq (,$(findstring CYGWIN,$(shell uname -s)))
-          # confirm user is using default cygwin unix Python (which uses ttySx) and not Windows Python (which uses COMx)
-          ifeq ($(shell which python),/usr/bin/python)
-            RESET_CMD = $(ARD_RESET_ARDUINO) $(ARD_RESET_OPTS) $(DEVICE_PATH)
-          else
-            RESET_CMD = $(ARD_RESET_ARDUINO) $(ARD_RESET_OPTS) $(call get_monitor_port)
-          endif
-        else
-            RESET_CMD = $(ARD_RESET_ARDUINO) $(ARD_RESET_OPTS) $(call get_monitor_port)
-        endif
+        RESET_CMD = $(ARD_RESET_ARDUINO) $(ARD_RESET_OPTS) $(call get_monitor_port)
     endif
 endif
 
@@ -815,7 +815,7 @@ ifeq ($(strip $(CHK_SOURCES)),)
                 $(call show_config_info,No .pde or .ino files found. If you are compiling .c or .cpp files then you need to explicitly include Arduino header files)
             else
                 #TODO: Support more than one file. https://github.com/sudar/Arduino-Makefile/issues/49
-                $(error Need exactly one .pde or .ino file. This makefile doesn't support multiple .ino/.pde files yet)
+                $(error Need exactly one .pde or .ino file. This makefile doesn\'t support multiple .ino/.pde files yet)
             endif
         endif
 
@@ -830,13 +830,26 @@ ifeq ($(strip $(NO_CORE)),)
         CORE_CPP_SRCS   = $(wildcard $(ARDUINO_CORE_PATH)/*.cpp)
         CORE_AS_SRCS    = $(wildcard $(ARDUINO_CORE_PATH)/*.S)
 
+        # USB Core if samd or sam
+        ifeq ($(findstring sam, $(strip $(ARCHITECTURE))), sam)
+            CORE_C_SRCS    += $(wildcard $(ARDUINO_CORE_PATH)/USB/*.c)
+            CORE_CPP_SRCS  += $(wildcard $(ARDUINO_CORE_PATH)/USB/*.cpp)
+        endif
+
         ifneq ($(strip $(NO_CORE_MAIN_CPP)),)
             CORE_CPP_SRCS := $(filter-out %main.cpp, $(CORE_CPP_SRCS))
             $(call show_config_info,NO_CORE_MAIN_CPP set so core library will not include main.cpp,[MANUAL])
         endif
 
+        # Put alt core variant file for M0 devices in OTHER_OJBS
+        ifdef ALT_CORE_CPP_SRCS
+            ALT_CORE_OBJ_FILES  = $(ALT_CORE_C_SRCS:.c=.c.o) $(ALT_CORE_CPP_SRCS:.cpp=.cpp.o) $(ALT_CORE_AS_SRCS:.S=.S.o)
+            OTHER_OBJS   := $(patsubst $(ALTERNATE_CORE_PATH)/variants/$(VARIANT)/%,  \
+                $(OBJDIR)/core/%,$(ALT_CORE_OBJ_FILES))
+        endif
+
         CORE_OBJ_FILES  = $(CORE_C_SRCS:.c=.c.o) $(CORE_CPP_SRCS:.cpp=.cpp.o) $(CORE_AS_SRCS:.S=.S.o)
-        CORE_OBJS       = $(patsubst $(ARDUINO_CORE_PATH)/%,  \
+        CORE_OBJS       += $(patsubst $(ARDUINO_CORE_PATH)/%,  \
                 $(OBJDIR)/core/%,$(CORE_OBJ_FILES))
     endif
 else
@@ -908,6 +921,7 @@ endif
 TARGET_HEX = $(OBJDIR)/$(TARGET).hex
 TARGET_ELF = $(OBJDIR)/$(TARGET).elf
 TARGET_EEP = $(OBJDIR)/$(TARGET).eep
+TARGET_BIN = $(OBJDIR)/$(TARGET).bin
 CORE_LIB   = $(OBJDIR)/libcore.a
 
 # Names of executables - chipKIT needs to override all to set paths to PIC32
@@ -1023,6 +1037,7 @@ endif
 
 # SoftwareSerial requires -Os (some delays are tuned for this optimization level)
 %SoftwareSerial.cpp.o : OPTIMIZATION_FLAGS = -Os
+%Uart.cpp.o : OPTIMIZATION_FLAGS = -Os
 
 ifndef MCU_FLAG_NAME
     MCU_FLAG_NAME = mmcu
@@ -1100,7 +1115,7 @@ ifeq ($(shell expr $(CC_VERNUM) '>' 490), 1)
 endif
 LDFLAGS       += -$(MCU_FLAG_NAME)=$(MCU) -Wl,--gc-sections -O$(OPTIMIZATION_LEVEL)
 ifeq ($(shell expr $(CC_VERNUM) '>' 490), 1)
-    LDFLAGS += -flto -fuse-linker-plugin
+		LDFLAGS += -flto -fuse-linker-plugin
 endif
 SIZEFLAGS     ?= --mcu=$(MCU) -C
 
@@ -1308,7 +1323,24 @@ $(OBJDIR)/core/%.S.o: $(ARDUINO_CORE_PATH)/%.S $(COMMON_DEPS) | $(OBJDIR)
 	@$(MKDIR) $(dir $@)
 	$(CC) -MMD -c $(CPPFLAGS) $(ASFLAGS) $< -o $@
 
+# alt core files
+$(OBJDIR)/core/%.c.o: $(ALTERNATE_CORE_PATH)/variants/$(VARIANT)/%.c $(COMMON_DEPS) | $(OBJDIR)
+	@$(MKDIR) $(dir $@)
+	$(CC) -MMD -c $(CPPFLAGS) $(CFLAGS) $< -o $@
+
+$(OBJDIR)/core/%.cpp.o: $(ALTERNATE_CORE_PATH)/variants/$(VARIANT)/%.cpp $(COMMON_DEPS) | $(OBJDIR)
+	@$(MKDIR) $(dir $@)
+	$(CXX) -MMD -c $(CPPFLAGS) $(CXXFLAGS) $< -o $@
+
+$(OBJDIR)/core/%.S.o: $(ALTERNATE_CORE_PATH)/variants/$(VARIANT)/%.S $(COMMON_DEPS) | $(OBJDIR)
+	@$(MKDIR) $(dir $@)
+	$(CC) -MMD -c $(CPPFLAGS) $(ASFLAGS) $< -o $@
+
 # various object conversions
+$(OBJDIR)/%.bin: $(OBJDIR)/%.elf $(COMMON_DEPS)
+	@$(MKDIR) $(dir $@)
+	-$(OBJCOPY) -O binary $< $@
+
 $(OBJDIR)/%.hex: $(OBJDIR)/%.elf $(COMMON_DEPS)
 	@$(MKDIR) $(dir $@)
 	$(OBJCOPY) -O ihex -R .eeprom $< $@
@@ -1448,12 +1480,21 @@ endif
 # so we do not set it by default.
 AVRDUDE_ISP_OPTS = -c $(ISP_PROG) -b $(AVRDUDE_ISP_BAUDRATE)
 
-ifndef $(ISP_PORT)
+ifndef ISP_PORT
     ifneq ($(strip $(ISP_PROG)),$(filter $(ISP_PROG), atmelice_isp usbasp usbtiny gpio linuxgpio avrispmkii dragon_isp dragon_dw))
-        AVRDUDE_ISP_OPTS += -P $(call get_isp_port)
+        # switch for sam devices as bootloader will be on usb serial if using stk500_v2
+        ifeq ($(findstring sam, $(strip $(ARCHITECTURE))), sam)
+            AVRDUDE_ISP_OPTS += -P $(call get_monitor_port)
+        else
+            AVRDUDE_ISP_OPTS += -P $(call get_isp_port)
+        endif
     endif
 else
-	AVRDUDE_ISP_OPTS += -P $(call get_isp_port)
+    ifeq ($(CURRENT_OS), WINDOWS)
+        AVRDUDE_ISP_OPT += -P ISP_PORT
+    else
+        AVRDUDE_ISP_OPTS += -P $(call get_isp_port)
+    endif
 endif
 
 ifndef ISP_EEPROM
@@ -1471,7 +1512,7 @@ endif
 ########################################################################
 # Explicit targets start here
 
-all: 		$(TARGET_EEP) $(TARGET_HEX)
+all: 		$(TARGET_EEP) $(TARGET_BIN) $(TARGET_HEX)
 
 # Rule to create $(OBJDIR) automatically. All rules with recipes that
 # create a file within it, but do not already depend on a file within it
@@ -1485,8 +1526,15 @@ $(OBJDIR): pre-build
 pre-build:
 		$(call runscript_if_exists,$(PRE_BUILD_HOOK))
 
+# copied from arduino with start-group, end-group
 $(TARGET_ELF): 	$(LOCAL_OBJS) $(CORE_LIB) $(OTHER_OBJS)
+# sam devices need start and end group
+ifeq ($(findstring sam, $(strip $(ARCHITECTURE))), sam)
+		$(CC) $(LINKER_SCRIPTS) -Wl,-Map=$(OBJDIR)/$(TARGET).map -o $@ $(LOCAL_OBJS) $(OTHER_OBJS) $(OTHER_LIBS) $(LDFLAGS) $(CORE_LIB) -Wl,--end-group
+# otherwise traditional
+else
 		$(CC) $(LDFLAGS) -o $@ $(LOCAL_OBJS) $(CORE_LIB) $(OTHER_OBJS) $(OTHER_LIBS) -lc -lm $(LINKER_SCRIPTS)
+endif
 
 $(CORE_LIB):	$(CORE_OBJS) $(LIB_OBJS) $(PLATFORM_LIB_OBJS) $(USER_LIB_OBJS)
 		$(AR) rcs $@ $(CORE_OBJS) $(LIB_OBJS) $(PLATFORM_LIB_OBJS) $(USER_LIB_OBJS)
@@ -1494,21 +1542,47 @@ $(CORE_LIB):	$(CORE_OBJS) $(LIB_OBJS) $(PLATFORM_LIB_OBJS) $(USER_LIB_OBJS)
 error_on_caterina:
 		$(ERROR_ON_CATERINA)
 
-
 # Use submake so we can guarantee the reset happens
 # before the upload, even with make -j
 upload:		$(TARGET_HEX) verify_size
+ifeq ($(findstring sam, $(strip $(ARCHITECTURE))), sam)
+# do reset toggle at 1200 BAUD to enter bootloader if using avrdude or bossa
+ifeq ($(strip $(UPLOAD_TOOL)), avrdude)
+		$(MAKE) reset
+else ifeq ($(findstring bossac, $(strip $(UPLOAD_TOOL))), bossac)
+		$(MAKE) reset
+endif
+		$(MAKE) do_sam_upload
+else
 		$(MAKE) reset
 		$(MAKE) do_upload
+endif
 
 raw_upload:	$(TARGET_HEX) verify_size
+ifeq ($(findstring sam, $(strip $(ARCHITECTURE))), sam)
+		$(MAKE) do_sam_upload
+else
 		$(MAKE) error_on_caterina
 		$(MAKE) do_upload
+endif
 
 do_upload:
 		$(AVRDUDE) $(AVRDUDE_COM_OPTS) $(AVRDUDE_ARD_OPTS) \
 			$(AVRDUDE_UPLOAD_HEX)
 
+do_sam_upload:  $(TARGET_BIN) verify_size
+ifeq ($(findstring openocd, $(strip $(UPLOAD_TOOL))), openocd)
+		$(OPENOCD) $(OPENOCD_OPTS) -c "telnet_port disabled; program {{$(TARGET_BIN)}} verify reset $(BOOTLOADER_SIZE); shutdown"
+else ifeq ($(findstring bossac, $(strip $(UPLOAD_TOOL))), bossac)
+		$(BOSSA) $(BOSSA_OPTS) $(TARGET_BIN)
+else ifeq ($(findstring gdb, $(strip $(UPLOAD_TOOL))), gdb)
+		$(GDB) $(GDB_UPLOAD_OPTS)
+else ifeq ($(strip $(UPLOAD_TOOL)), avrdude)
+		$(MAKE) ispload
+else
+		@$(ECHO) "$(BOOTLOADER_UPLOAD_TOOL) not currently supported!\n\n"
+endif
+
 do_eeprom:	$(TARGET_EEP) $(TARGET_HEX)
 		$(AVRDUDE) $(AVRDUDE_COM_OPTS) $(AVRDUDE_ARD_OPTS) \
 			$(AVRDUDE_UPLOAD_EEP)
@@ -1541,14 +1615,22 @@ ispload:	$(TARGET_EEP) $(TARGET_HEX) verify_size
 			$(AVRDUDE_ISPLOAD_OPTS)
 
 burn_bootloader:
-ifneq ($(strip $(AVRDUDE_ISP_FUSES_PRE)),)
-		$(AVRDUDE) $(AVRDUDE_COM_OPTS) $(AVRDUDE_ISP_OPTS) -e $(AVRDUDE_ISP_FUSES_PRE)
-endif
-ifneq ($(strip $(AVRDUDE_ISP_BURN_BOOTLOADER)),)
-		$(AVRDUDE) $(AVRDUDE_COM_OPTS) $(AVRDUDE_ISP_OPTS) $(AVRDUDE_ISP_BURN_BOOTLOADER)
-endif
-ifneq ($(strip $(AVRDUDE_ISP_FUSES_POST)),)
-		$(AVRDUDE) $(AVRDUDE_COM_OPTS) $(AVRDUDE_ISP_OPTS) $(AVRDUDE_ISP_FUSES_POST)
+ifeq ($(findstring sam, $(strip $(ARCHITECTURE))), sam)
+    ifeq ($(strip $(BOOTLOADER_UPLOAD_TOOL)), openocd)
+				$(OPENOCD) $(OPENOCD_OPTS) -c "telnet_port disabled; init; halt; $(BOOTLOADER_UNPROTECT); program {{$(BOOTLOADER_PARENT)/$(BOOTLOADER_FILE)}} verify reset; shutdown"
+    else
+				@$(ECHO) "$(BOOTLOADER_UPLOAD_TOOL) not currently supported!\n\n"
+    endif
+else
+    ifneq ($(strip $(AVRDUDE_ISP_FUSES_PRE)),)
+				$(AVRDUDE) $(AVRDUDE_COM_OPTS) $(AVRDUDE_ISP_OPTS) -e $(AVRDUDE_ISP_FUSES_PRE)
+    endif
+    ifneq ($(strip $(AVRDUDE_ISP_BURN_BOOTLOADER)),)
+				$(AVRDUDE) $(AVRDUDE_COM_OPTS) $(AVRDUDE_ISP_OPTS) $(AVRDUDE_ISP_BURN_BOOTLOADER)
+    endif
+    ifneq ($(strip $(AVRDUDE_ISP_FUSES_POST)),)
+				$(AVRDUDE) $(AVRDUDE_COM_OPTS) $(AVRDUDE_ISP_OPTS) $(AVRDUDE_ISP_FUSES_POST)
+    endif
 endif
 
 set_fuses:
@@ -1586,6 +1668,12 @@ else
 		$(MONITOR_CMD) $(call get_monitor_port) $(MONITOR_BAUDRATE)
 endif
 
+debug_init:
+	$(OPENOCD)
+
+debug:
+	$(GDB) $(GDB_OPTS)
+
 disasm: $(OBJDIR)/$(TARGET).lss
 		@$(ECHO) "The compiled ELF file has been disassembled to $(OBJDIR)/$(TARGET).lss\n\n"
 
@@ -1605,7 +1693,6 @@ generate_assembly: $(OBJDIR)/$(TARGET).s
 generated_assembly: generate_assembly
 		@$(ECHO) "\"generated_assembly\" target is deprecated. Use \"generate_assembly\" target instead\n\n"
 
-.PHONY: tags
 tags:
 ifneq ($(words $(wildcard $(TAGS_FILE))), 0)
 	rm -f $(TAGS_FILE)
@@ -1640,6 +1727,8 @@ help:
   make show_boards       - list all the boards defined in boards.txt\n\
   make show_submenu      - list all board submenus defined in boards.txt\n\
   make monitor           - connect to the Arduino's serial port\n\
+  make debug_init        - start openocd gdb server\n\
+  make debug             - connect to gdb target and begin debugging\n\
   make size              - show the size of the compiled output (relative to\n\
                            resources, if you have a patched avr-size).\n\
   make verify_size       - verify that the size of the final file is less than\n\
@@ -1661,7 +1750,7 @@ help:
 
 .PHONY: all upload raw_upload raw_eeprom error_on_caterina reset reset_stty ispload \
         clean depends size show_boards monitor disasm symbol_sizes generated_assembly \
-        generate_assembly verify_size burn_bootloader help pre-build
+        generate_assembly verify_size burn_bootloader help pre-build tags debug debug_init
 
 # added - in the beginning, so that we don't get an error if the file is not present
 -include $(DEPS)
diff --git a/Common.mk b/Common.mk
index a8bd46a..5f30fba 100644
--- a/Common.mk
+++ b/Common.mk
@@ -1,3 +1,4 @@
+COMMON_INCLUDED = TRUE
 # Useful functions
 # Returns the first argument (typically a directory), if the file or directory
 # named by concatenating the first and optionally second argument
@@ -26,8 +27,11 @@ show_config_variable = $(call show_config_info,$(1) = $($(1)) $(3),$(2))
 # Just a nice simple visual separator
 show_separator = $(call arduino_output,-------------------------)
 
+# Master Arduino Makefile include (after user Makefile)
+ardmk_include = $(shell basename $(word 2,$(MAKEFILE_LIST)))
+
 $(call show_separator)
-$(call arduino_output,Arduino.mk Configuration:)
+$(call arduino_output,$(call ardmk_include) Configuration:)
 
 ########################################################################
 #
diff --git a/HISTORY.md b/HISTORY.md
index e18a065..434ed96 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -19,6 +19,7 @@ I tried to give credit whenever possible. If I have missed anyone, kindly add it
 - New: Add template Makefile and project boilerplate initialise script, `ardmk-init`. (https://github.com/tuna-f1sh)
 - New: Support atmelice_isp JTAG tool as ISP programmer. (https://github.com/tuna-f1sh)
 - New: Compatibility with deprecated pgmspace.h API can now be disabled since it sometimes causes bogus compiler warnings (issue #546)
+- New: Support Arduino ARM-based (SAM/SAMD) devices. (https://github.com/tuna-f1sh)
 
 ### 1.6.0 (2017-07-11)
 - Fix: Allowed for SparkFun's weird usb pid/vid submenu shenanigans (issue #499). (https://github.com/sej7278)
diff --git a/README.md b/README.md
index 953d067..f3b5e20 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,8 @@ This is a very simple Makefile which knows how to build Arduino sketches. It def
 - Very robust
 - Highly customizable
 - Supports all official AVR-based Arduino boards
+- Supports official ARM-based Arduino boards using Atmel SAM chip family
+  (Cortex M0) and includes on-device debugging targets.
 - Supports chipKIT
 - Supports Teensy 3.x (via Teensyduino)
 - Works on all three major OS (Mac, Linux, Windows)
@@ -313,6 +315,72 @@ See examples/BlinkOpenCM for example usage.
 
 For large Robotis projects, [libmaple](https://github.com/Rhoban/Maple) may be more appropriate, as the OpenCM IDE uses a very old compiler release.
 
+## Arduino ARM Boards
+
+For Arduino boards using ARM architechure, specifically the Atmel SAM series
+(Arduino M0 [Pro], Zero, MKR1000, Feather M0, etc.), first
+install the board support package from the IDE or other distribution channels.
+
+Define`ARDUINO_PACKAGE_DIR` as the root path containing the ARM support
+package (the manufacturer folder) and the `BOARD_TAG` (see `make show_boards`
+for help) within your project Makefile. Include 'Sam.mk' rather than
+  'Arduino.mk' at the end of your file - see examples/ZeroBlink and
+  examples/MZeroBlink for example usage.
+
+**Note**: The Arduino IDE does not install board support packages to
+the base Arduino installation directory (the directory that will work with AVR
+Makefiles). They are generally installed to a '.arduino15/packages' folder in
+the users home directory. This is the reason for the new `ARDUINO_PACKAGE_DIR`
+define. On Windows, the package directory is often in the user home directory
+so advice is to create a symblic link to avoid slash/space in path problems.
+You can also manually install support packages in your Sketchbook 'hardware'
+folder, then define ARDUINO_PACKAGE_DIR as this path.
+
+If using a SAM board from a manufacturer other than Arduino, one must still
+install the Arduino board support as above (unless using externally defined
+toolchain) and then define the location of the manufacturer board support core
+using the ALTERNATIVE_CORE_PATH define. For example: `ALTERNATE_CORE_PATH =
+$(ARDUINO_SKETCHBOOK)/hardware/sparkfun/samd`
+
+The programing method will auto-detect based on the `BOARD_TAG` settings read
+from boards.txt:
+
+Programming using OpenOCD CMSIS-DAP with the Programming/debug USB is
+currently supported (the same method used by the IDE), including burning
+bootloaders. External CMSIS tools such as Atmel Ice will also work with this
+method. Black Magic Probe (BMP) support is also included using GDB for both
+uploading and debugging.
+
+Native USB programing using Bossa (Zero, MKR1000, Feather style bootloaders)
+and avrdude (M0 bootloaders) is supported. The bootloaders on these devices
+requires a double press of the reset button or open/closing the serial port at
+1200 BAUD. The automatic entry of the bootloader is attempted using
+`ard-reset-arduino` when using the general `make upload` target by polling
+attached devices until the bootloader port re-attaches (same method as the
+IDE). On Windows, the USB enumerates as differnt COM ports for the CDC Serial
+and bootloader and these must be defined. On encountering problems, one can
+manually enter the bootloader then upload using the `make raw_upload` target.
+Note that the `make reset` target will enter the bootloader on these devices;
+there is no way to reset over USB.
+
+If using system installed tools, be aware that `openocd` and `bossa` were
+orginally forked for Arduino support and system distributions may not be up
+to date with merged changes. `bossa` must be version 1.7->. `openocd` should
+work but there may be problems at run time
+[ref](https://github.com/pda/arduino-zero-without-ide). Ideally, use the
+support packaged version or compile and install the Arduino fork.
+
+With the ARM chipset and using a CMSIS-DAP tool, on-device debugging is made available:
+
+* `debug_init` and `debug` targets for on-device debugging using GDB. To use
+  this, one must start the GDB server with `make debug_init &`, followed by
+  connecting to the target with `make debug`. If using a Black Magic Probe,
+  one can just use `make debug`. At the moment, a system wide `arm-none-eabi-gdb` must be
+  installed as the one supplied with the Arduino toolchain
+  does not appear to work. 
+* Example usage: https://asciinema.org/a/Jarz7Pr3gD6mqaZvCACQBzqix
+* See the examples/MZeroBlink Makefile for a commented example.
+
 ## Versioning
 
 The current version of the makefile is `1.6.0`. You can find the full history in the [HISTORY.md](HISTORY.md) file
@@ -332,9 +400,8 @@ Also checkout the [contribution guide](CONTRIBUTING.md) for more details.
 
 If you are looking for ideas to work on, then check out the following TODO items or the [issue tracker](https://github.com/sudar/Arduino-Makefile/issues/).
 
-## Limitations / Know Issues / TODO's
+## Limitations / Known Issues / TODO's
 
-- Doesn't support SAM boards yet.
 - Since it doesn't do any pre processing like Arduino IDE, you have to declare all methods before you use them ([issue #59](https://github.com/sudar/Arduino-Makefile/issues/59))
 - More than one .ino or .pde file is not supported yet ([issue #49](https://github.com/sudar/Arduino-Makefile/issues/49))
 - When you compile for the first time, it builds all libs inside Arduino directory even if it is not needed. But while linking only the relevant files are linked. ([issue #29](https://github.com/sudar/Arduino-Makefile/issues/29)). Even Arduino IDE does the same thing though.
diff --git a/Sam.mk b/Sam.mk
new file mode 100644
index 0000000..8b93ee4
--- /dev/null
+++ b/Sam.mk
@@ -0,0 +1,481 @@
+########################################################################
+#
+# Support for Arduino Atmel SAM boards (sam and samd)
+#
+# You must install a SAM board hardware support package (such as Arduino Zero)
+# to use this, then define ARDUINO_PACKAGE_DIR as the path to the root
+# directory containing the support package.
+#
+# 2018 John Whittington @j_whittington
+#
+########################################################################
+
+arduino_output =
+# When output is not suppressed and we're in the top-level makefile,
+# running for the first time (i.e., not after a restart after
+# regenerating the dependency file), then output the configuration.
+ifndef ARDUINO_QUIET
+    ifeq ($(MAKE_RESTARTS),)
+        ifeq ($(MAKELEVEL),0)
+            arduino_output = $(info $(1))
+        endif
+    endif
+endif
+
+ifndef ARDMK_DIR
+    ARDMK_DIR := $(realpath $(dir $(realpath $(lastword $(MAKEFILE_LIST)))))
+endif
+
+# include Common.mk now we know where it is
+ifndef COMMON_INCLUDED
+    include $(ARDMK_DIR)/Common.mk
+endif
+
+ifndef ARDUINO_PACKAGE_DIR
+    # attempt to find based on Linux, macOS and Windows default
+    ARDUINO_PACKAGE_DIR := $(firstword \
+        $(call dir_if_exists,$(HOME)/.arduino15/packages) \
+        $(call dir_if_exists,$(ARDUINO_DIR)/packages) \
+        $(call dir_if_exists,$(HOME)/Library/Arduino15/packages) \
+        $(call dir_if_exists,$(USERPROFILE)/AppData/Local/Arduino15/packages) )
+    $(call show_config_variable,ARDUINO_PACKAGE_DIR,[AUTODETECTED],(from DEFAULT))
+else
+    $(call show_config_variable,ARDUINO_PACKAGE_DIR,[USER])
+endif
+
+ifndef ARDMK_VENDOR
+    ARDMK_VENDOR := arduino
+endif
+
+ifndef ARCHITECTURE
+    ARCHITECTURE := samd
+endif
+
+ifndef CORE_VER
+    CORE_VER := $(wildcard $(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/hardware/$(ARCHITECTURE)/1.*)
+    ifdef CORE_VER
+        CORE_VER := $(shell basename $(CORE_VER))
+        $(call show_config_variable,CORE_VER,[AUTODETECTED],(from ARDUINO_PACKAGE_DIR))
+    endif
+else
+    $(call show_config_variable,CORE_VER,[USER])
+endif
+
+ifndef CMSIS_VER
+    CMSIS_VER := $(shell basename $(wildcard $(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/tools/CMSIS/4.*))
+    $(call show_config_variable,CMSIS_VER,[AUTODETECTED],(from ARDUINO_PACKAGE_DIR))
+else
+    $(call show_config_variable,CMSIS_VER,[USER])
+endif
+
+ifndef CMSIS_ATMEL_VER
+    CMSIS_ATMEL_VER := $(shell basename $(wildcard $(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/tools/CMSIS-Atmel/1.*))
+    $(call show_config_variable,CMSIS_ATMEL_VER,[AUTODETECTED],(from ARDUINO_PACKAGE_DIR))
+else
+    $(call show_config_variable,CMSIS_ATMEL_VER,[USER])
+endif
+
+ifndef CMSIS_DIR
+    CMSIS_DIR := $(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/tools/CMSIS/$(CMSIS_VER)/CMSIS
+    $(call show_config_variable,CMSIS_DIR,[AUTODETECTED],(from ARDUINO_PACKAGE_DIR))
+else
+    $(call show_config_variable,CMSIS_DIR,[USER])
+endif
+
+ifndef CMSIS_ATMEL_DIR
+    CMSIS_ATMEL_DIR := $(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/tools/CMSIS-Atmel/$(CMSIS_ATMEL_VER)/CMSIS
+    $(call show_config_variable,CMSIS_ATMEL_DIR,[AUTODETECTED],(from ARDUINO_PACKAGE_DIR))
+else
+    $(call show_config_variable,CMSIS_ATMEL_DIR,[USER])
+endif
+
+# Arduino Settings (will get shown in Arduino.mk as computed)
+ifndef ALTERNATE_CORE_PATH
+    ifdef CORE_VER
+        ALTERNATE_CORE_PATH = $(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/hardware/$(ARCHITECTURE)/$(CORE_VER)
+    else
+        ALTERNATE_CORE_PATH = $(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/hardware/$(ARCHITECTURE)
+    endif
+endif
+ifndef ARDUINO_CORE_PATH
+    ARDUINO_CORE_PATH   = $(ALTERNATE_CORE_PATH)/cores/arduino
+endif
+ifndef BOARD_TXT
+    BOARDS_TXT          = $(ALTERNATE_CORE_PATH)/boards.txt
+endif
+
+# Check boards file exists before continuing as parsing non-existant file can create problems
+ifneq ($(findstring boards.txt, $(wildcard $(ALTERNATE_CORE_PATH)/*.txt)), boards.txt)
+    echo $(error $(CORE_VER) Cannot find boards file $(BOARDS_TXT). Check ARDUINO_PACKAGE_DIR path: $(ARDUINO_PACKAGE_DIR) and board support installed)
+endif
+
+# add CMSIS includes
+CPPFLAGS += -I$(CMSIS_DIR)/Include/
+CPPFLAGS += -I$(CMSIS_ATMEL_DIR)/Device/ATMEL
+# path for Cortex library
+LIB_PATH  =  $(CMSIS_DIR)/Lib/GCC
+BOOTLOADER_PARENT = $(ALTERNATE_CORE_PATH)/bootloaders
+
+# Utility from ard-mk to parse boards.txt for flags
+ifndef PARSE_BOARD
+    PARSE_BOARD = $(shell grep -Ev '^\#' $(BOARDS_TXT) | grep -E '^[ \t]*$(1).$(2)=' | cut -d = -f 2 | cut -d : -f 2)
+endif
+
+ifndef VARIANT
+    VARIANT := $(call PARSE_BOARD,$(BOARD_TAG),menu.(chip|cpu).$(BOARD_SUB).build.variant)
+    ifndef VARIANT
+        VARIANT := $(call PARSE_BOARD,$(BOARD_TAG),build.variant)
+    endif
+endif
+
+# grab any sources in the variant core path (variant.cpp defines pin/port mapping on SAM devices)
+ALT_CORE_C_SRCS := $(wildcard $(ALTERNATE_CORE_PATH)/variants/$(VARIANT)/*.c)
+ALT_CORE_CPP_SRCS := $(wildcard $(ALTERNATE_CORE_PATH)/variants/$(VARIANT)/*.cpp)
+ALT_CORE_S_SRCS := $(wildcard $(ALTERNATE_CORE_PATH)/variants/$(VARIANT)/*.S)
+
+# Use arm-toolchain from Arduino install if exists and user has not defined global version
+ifndef ARM_TOOLS_DIR
+    ARM_TOOLS_DIR = $(call dir_if_exists,$(wildcard $(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/tools/arm-none-eabi-gcc/*))
+    $(call show_config_variable,ARM_TOOLS_DIR,[COMPUTED],(from ARDUINO_PACKAGE_DIR))
+else
+    $(call show_config_variable,ARM_TOOLS_DIR,[USER])
+endif
+
+# define plaform lib dir from Arduino ARM support
+ifndef ARDUINO_PLATFORM_LIB_PATH
+    ARDUINO_PLATFORM_LIB_PATH := $(ALTERNATE_CORE_PATH)/libraries
+    $(call show_config_variable,ARDUINO_PLATFORM_LIB_PATH,[COMPUTED],(from ARDUINO_PACKAGE_DIR))
+endif
+
+########################################################################
+# command names
+
+ifndef CC_NAME
+    CC_NAME := $(call PARSE_BOARD,$(BOARD_TAG),build.command.gcc)
+    ifndef CC_NAME
+        CC_NAME := arm-none-eabi-gcc
+    else
+        $(call show_config_variable,CC_NAME,[COMPUTED])
+    endif
+endif
+
+ifndef CXX_NAME
+    CXX_NAME := $(call PARSE_BOARD,$(BOARD_TAG),build.command.g++)
+    ifndef CXX_NAME
+        CXX_NAME := arm-none-eabi-g++
+    else
+        $(call show_config_variable,CXX_NAME,[COMPUTED])
+    endif
+endif
+
+ifndef AS_NAME
+    AS_NAME := $(call PARSE_BOARD,$(BOARD_TAG),build.command.as)
+    ifndef AS_NAME
+        AS_NAME := arm-none-eabi-gcc-as
+    else
+        $(call show_config_variable,AS_NAME,[COMPUTED])
+    endif
+endif
+
+ifndef OBJCOPY_NAME
+    OBJCOPY_NAME := $(call PARSE_BOARD,$(BOARD_TAG),build.command.objcopy)
+    ifndef OBJCOPY_NAME
+        OBJCOPY_NAME := arm-none-eabi-objcopy
+    else
+        $(call show_config_variable,OBJCOPY_NAME,[COMPUTED])
+    endif
+endif
+
+ifndef OBJDUMP_NAME
+    OBJDUMP_NAME := $(call PARSE_BOARD,$(BOARD_TAG),build.command.objdump)
+    ifndef OBJDUMP_NAME
+        OBJDUMP_NAME := arm-none-eabi-objdump
+    else
+        $(call show_config_variable,OBJDUMP_NAME,[COMPUTED])
+    endif
+endif
+
+ifndef AR_NAME
+    AR_NAME := $(call PARSE_BOARD,$(BOARD_TAG),build.command.ar)
+    ifndef AR_NAME
+        AR_NAME := arm-none-eabi-ar
+    else
+        $(call show_config_variable,AR_NAME,[COMPUTED])
+    endif
+endif
+
+ifndef SIZE_NAME
+    SIZE_NAME := $(call PARSE_BOARD,$(BOARD_TAG),build.command.size)
+    ifndef SIZE_NAME
+        SIZE_NAME := arm-none-eabi-size
+    else
+        $(call show_config_variable,SIZE_NAME,[COMPUTED])
+    endif
+endif
+
+ifndef NM_NAME
+    NM_NAME := $(call PARSE_BOARD,$(BOARD_TAG),build.command.nm)
+    ifndef NM_NAME
+        NM_NAME := arm-none-eabi-gcc-nm
+    else
+        $(call show_config_variable,NM_NAME,[COMPUTED])
+    endif
+endif
+
+ifndef GDB_NAME
+    GDB_NAME := $(call PARSE_BOARD,$(BOARD_TAG),build.command.gdb)
+    ifndef GDB_NAME
+        GDB_NAME := arm-none-eabi-gdb
+    else
+        $(call show_config_variable,GDB_NAME,[COMPUTED])
+    endif
+endif
+
+ifndef UPLOAD_TOOL
+    UPLOAD_TOOL := $(call PARSE_BOARD,$(BOARD_TAG),upload.tool)
+    ifndef UPLOAD_TOOL
+        UPLOAD_TOOL := openocd
+    else
+        $(call show_config_variable,UPLOAD_TOOL,[COMPUTED])
+    endif
+endif
+
+ifndef BOOTLOADER_UPLOAD_TOOL
+    BOOTLOADER_UPLOAD_TOOL := $(call PARSE_BOARD,$(BOARD_TAG),bootloader.tool)
+    ifndef BOOTLOADER_UPLOAD_TOOL
+        BOOTLOADER_UPLOAD_TOOL := openocd
+    else
+        $(call show_config_variable,BOOTLOADER_UPLOAD_TOOL,[COMPUTED])
+    endif
+endif
+
+# processor stuff
+ifndef MCU
+    MCU := $(call PARSE_BOARD,$(BOARD_TAG),build.mcu)
+endif
+
+ifndef MCU_FLAG_NAME
+    MCU_FLAG_NAME=mcpu
+endif
+
+# native port emulates an AVR chip to use AVRDUDE
+ifndef AVRDUDE_MCU
+    AVRDUDE_MCU := $(call PARSE_BOARD,$(BOARD_TAG),build.emu.mcu)
+endif
+
+# GDP settings
+ifndef GDB_PORT
+    # default to localhost default OpenOCD port
+    GDB_PORT = localhost:3333
+endif
+
+ifndef GDB_OPTS
+    # if using BMP do a scan and attach
+    ifeq ($(findstring /dev/tty, $(strip $(GDB_PORT))), /dev/tty)
+        GDB_OPTS = -ex "target extended-remote $(GDB_PORT)" -ex "monitor swdp_scan" -ex "attach 1" -ex "load" -d $(OBJDIR) $(TARGET_ELF)
+    else
+        GDB_OPTS = -ex "target extended-remote $(GDB_PORT)" -ex "load" -d $(OBJDIR) $(TARGET_ELF)
+    endif
+endif
+
+ifndef GDB_UPLOAD_OPTS
+    GDB_UPLOAD_OPTS = $(GDB_OPTS) -ex "set confirm off" -ex "set target-async off" -ex "set remotetimeout 30" -ex "detach" -ex "kill" -ex "quit"
+endif
+
+########################################################################
+# OpenOCD for SAM devices
+
+ifndef OPENOCD
+    BUNDLED_OPENOCD_DIR := $(call dir_if_exists,$(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/tools/openocd)
+    # Try Arduino support package first
+    ifdef BUNDLED_OPENOCD_DIR
+        OPENOCD_VER := $(shell basename $(wildcard $(BUNDLED_OPENOCD_DIR)/*))
+        OPENOCD = $(BUNDLED_OPENOCD_DIR)/$(OPENOCD_VER)/bin/openocd -s $(BUNDLED_OPENOCD_DIR)/$(OPENOCD_VER)/share/openocd/scripts/
+        $(call show_config_variable,OPENOCD,[AUTODETECTED],(from ARDUINO_PACKAGE_DIR))
+    else
+        # Otherwise look on user path
+        OPENOCD := $(shell which openocd 2>/dev/null)
+        ifdef OPENOCD
+            $(call show_config_variable,OPENOCD,[AUTODETECTED],(found in $$PATH))
+        endif
+    endif
+else
+    $(call show_config_variable,OPENOCD,[USER])
+endif
+
+ifndef OPENOCD_OPTS
+    OPENOCD_OPTS += -d2 -f $(ALTERNATE_CORE_PATH)/variants/$(VARIANT)/$(OPENOCD_SCRIPT)
+endif
+
+########################################################################
+# Bossa for SAM devices
+
+ifndef BOSSA
+    BUNDLED_BOSSA_DIR := $(call dir_if_exists,$(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/tools/bossac)
+    # Try Arduino support package first
+    ifdef BUNDLED_BOSSA_DIR
+        BOSSA_VER := $(shell basename $(wildcard $(BUNDLED_BOSSA_DIR)/*))
+        BOSSA = $(BUNDLED_BOSSA_DIR)/$(BOSSA_VER)/bossac
+        $(call show_config_variable,BOSSA,[AUTODETECTED],(from ARDUINO_PACKAGE_DIR))
+    else
+        # Otherwise look on user path
+        BOSSA := $(shell which bossac 2>/dev/null)
+        ifdef BOSSA
+            $(call show_config_variable,BOSSA,[AUTODETECTED],(found in $$PATH))
+        endif
+    endif
+else
+    $(call show_config_variable,BOSSA,[USER])
+endif
+
+ifndef BOSSA_OPTS
+    BOSSA_OPTS += -d --info --erase --write --verify --reset
+endif
+
+get_bootloader = $(shell $(RESET_CMD) | tail -1)
+
+# if not bootloader port defined (ISP_PORT), automatically grab first port after reset
+# if not on windows
+ifndef ISP_PORT
+    ifeq ($(CURRENT_OS), WINDOWS)
+        BOSSA_OPTS += --port=$(COM_STYLE_MONITOR_PORT)
+    else
+        BOSSA_OPTS += --port=$(call get_monitor_port)
+    endif
+else
+    BOSSA_OPTS += --port=$(ISP_PORT)
+endif
+
+########################################################################
+# EXECUTABLES
+# Define them here to use ARM_TOOLS_PATH and allow auto finding of AVR_TOOLS_PATH
+OVERRIDE_EXECUTABLES = 1
+
+ARM_TOOLS_PATH := $(ARM_TOOLS_DIR)/bin
+CC      = $(ARM_TOOLS_PATH)/$(CC_NAME)
+CXX     = $(ARM_TOOLS_PATH)/$(CXX_NAME)
+AS      = $(ARM_TOOLS_PATH)/$(AS_NAME)
+OBJCOPY = $(ARM_TOOLS_PATH)/$(OBJCOPY_NAME)
+OBJDUMP = $(ARM_TOOLS_PATH)/$(OBJDUMP_NAME)
+AR      = $(ARM_TOOLS_PATH)/$(AR_NAME)
+SIZE    = $(ARM_TOOLS_PATH)/$(SIZE_NAME)
+NM      = $(ARM_TOOLS_PATH)/$(NM_NAME)
+#GDB     = $(ARM_TOOLS_PATH)/$(GDB_NAME)
+# Use system gdb for now as Arduino supplied has lib error?
+GDB     = $(GDB_NAME)
+
+########################################################################
+# FLAGS
+
+ifndef USB_TYPE
+    USB_TYPE = USBCON
+endif
+
+ifndef USB_PRODUCT
+    USB_PRODUCT := $(call PARSE_BOARD,$(BOARD_TAG),build.usb_product)
+    ifdef USB_PRODUCT
+        $(call show_config_variable,USB_PRODUCT,[COMPUTED])
+    endif
+endif
+
+ifndef USB_MANUFACTURER
+    USB_MANUFACTURER := $(call PARSE_BOARD,$(BOARD_TAG),build.usb_manufacturer)
+    ifndef USB_MANUFACTURER
+        USB_MANUFACTURER = "Unknown"
+    else
+        $(call show_config_variable,USB_MANUFACTURER,[COMPUTED])
+    endif
+endif
+
+ifndef USB_VID
+    USB_VID := $(call PARSE_BOARD,$(BOARD_TAG),build.vid)
+    ifdef USB_VID
+        $(call show_config_variable,USB_VID,[COMPUTED])
+    endif
+endif
+
+ifndef USB_PID
+    USB_PID := $(call PARSE_BOARD,$(BOARD_TAG),build.pid)
+    ifdef USB_PID
+        $(call show_config_variable,USB_PID,[COMPUTED])
+    endif
+endif
+
+# Bootloader settings
+ifndef BOOTLOADER_SIZE
+    BOOTLOADER_SIZE := $(call PARSE_BOARD,$(BOARD_TAG),bootloader.size)
+    ifndef BOOTLOADER_SIZE
+        BOOTLOADER_SIZE := 0x2000
+    else
+        $(call show_config_variable,BOOTLOADER_SIZE,[COMPUTED])
+    endif
+endif
+
+ifndef BOOTLOADER_UNPROTECT
+    BOOTLOADER_UNPROTECT := $(call PARSE_BOARD,$(BOARD_TAG),bootloader.cmd_unprotect)
+    ifndef BOOTLOADER_UNPROTECT
+        BOOTLOADER_UNPROTECT := at91samd bootloader 0
+    else
+        $(call show_config_variable,BOOTLOADER_UNPROTECT,[COMPUTED])
+    endif
+endif
+
+ifndef BOOTLOADER_PROTECT
+    BOOTLOADER_PROTECT := $(call PARSE_BOARD,$(BOARD_TAG),bootloader.cmd_protect)
+    ifndef BOOTLOADER_PROTECT
+        BOOTLOADER_PROTECT := at91samd bootloader 16384
+    else
+        $(call show_config_variable,BOOTLOADER_PROTECT,[COMPUTED])
+    endif
+endif
+
+ifndef BOOTLOADER_PROTECT_VERIFY
+    BOOTLOADER_PROTECT_VERIFY := $(call PARSE_BOARD,$(BOARD_TAG),bootloader.cmd_protect_verify)
+    ifndef BOOTLOADER_PROTECT_VERIFY
+        BOOTLOADER_PROTECT_VERIFY := at91samd bootloader
+    else
+        $(call show_config_variable,BOOTLOADER_PROTECT_VERIFY,[COMPUTED])
+    endif
+endif
+
+# C99 with GNU extensions required for C sources using old compiler
+CC_VERNUM = $(shell $(CC) -dumpversion | sed 's/\.//g')
+ifneq ($(shell expr $(CC_VERNUM) '>' 490), 1)
+    CFLAGS_STD        = -std=gnu99
+endif
+
+CPPFLAGS += -DMD -D$(USB_TYPE) '-DUSB_PRODUCT=$(USB_PRODUCT)' '-DUSB_MANUFACTURER=$(USB_MANUFACTURER)'
+
+# Get extra define flags from boards.txt
+EXFLAGS := $(shell echo $(call PARSE_BOARD,$(BOARD_TAG),build.extra_flags) | grep -oE '(-D)\w+')
+
+# Strip only defines from extra flags as boards file appends user {build.usb}
+CPPFLAGS += $(EXFLAGS)
+CPPFLAGS += -DUSB_VID=$(USB_VID)
+CPPFLAGS += -DUSB_PID=$(USB_PID)
+# Cortex compiler flags
+CPPFLAGS += -mthumb -nostdlib --param max-inline-insns-single=500 -fno-exceptions -Wl,-Map=$(OBJDIR)/$(TARGET).map
+CXXFLAGS += -fno-rtti -fno-threadsafe-statics -std=gnu++11
+
+AMCU := $(call PARSE_BOARD,$(BOARD_TAG),build.mcu)
+BOARD_LINKER_SCRIPT := $(call PARSE_BOARD,$(BOARD_TAG),build.ldscript)
+OPENOCD_SCRIPT := $(call PARSE_BOARD,$(BOARD_TAG),build.openocdscript)
+# TODO Hard defines Cortex M0 math lib - should be dynamic
+LDFLAGS += --specs=nano.specs --specs=nosys.specs -mthumb -Wl,--cref -Wl,--check-sections -Wl,--gc-sections -Wl,--unresolved-symbols=report-all -Wl,--warn-common -Wl,--warn-section-align -Wl,--start-group -L$(LIB_PATH) -larm_cortexM0l_math -lm
+LINKER_SCRIPTS := -T$(ALTERNATE_CORE_PATH)/variants/$(VARIANT)/$(BOARD_LINKER_SCRIPT)
+OTHER_LIBS := $(call PARSE_BOARD,$(BOARD_TAG),build.flags.libs)
+
+# OpenOCD reset command only for now
+ifeq ($(strip $(UPLOAD_TOOL)), openocd)
+    RESET_CMD = $(OPENOCD) $(OPENOCD_OPTS) -c "telnet_port disabled; init; targets; reset run; shutdown"
+else
+    # Set zero flag for ard-reset for 1200 baud boot to bootloader
+    ARD_RESET_OPTS += --zero
+endif
+
+########################################################################
+# automatially include Arduino.mk for the user
+
+$(call show_separator)
+$(call arduino_output,Arduino.mk Configuration:)
+include $(ARDMK_DIR)/Arduino.mk
diff --git a/Teensy.mk b/Teensy.mk
index 8bd822b..3d0114c 100644
--- a/Teensy.mk
+++ b/Teensy.mk
@@ -146,7 +146,7 @@ endif
 
 # processor stuff
 ifndef MCU
-    MCU := $(call PARSE_TEENSY,$(BOARD_TAG),build.cpu)
+    MCU := $(call PARSE_TEENSY,$(BOARD_TAG),build.mcu)
 endif
 
 ifndef MCU_FLAG_NAME
diff --git a/arduino-mk-vars.md b/arduino-mk-vars.md
index d19d3d6..e3b6f07 100644
--- a/arduino-mk-vars.md
+++ b/arduino-mk-vars.md
@@ -11,6 +11,7 @@ The following are the different variables that can be overwritten in the user ma
 *	[Avrdude setting variables](#avrdude-setting-variables)
 *	[Bootloader variables](#bootloader-variables)
 *	[ChipKIT variables](#chipkit-variables)
+*	[ARM variables](#arm-variables)
 *	[Ctags variables](#ctags-variables)
 
 ## Global variables
@@ -73,6 +74,29 @@ AVR_TOOLS_DIR = /usr/share/arduino/hardware/tools/avr
 
 ----
 
+### ARM_TOOLS_DIR
+
+**Description:**
+
+Directory where the arm toolchain is installed. `arm-none-eabi-*` should be
+within a /bin subdirectory.
+
+Can usually be detected from `$ARDUINO_PACKAGE_DIR` /tools subdirectory when ARM
+device support is installed.
+
+**Example:**
+
+```Makefile
+ARM_TOOLS_DIR = /usr
+# or
+ARM_TOOLS_DIR =
+/usr/share/arduino/hardware/tools/arm-none-eabi-gcc/VERSION
+```
+
+**Requirement:** *Optional*
+
+----
+
 ### RESET_CMD
 
 **Description:**
@@ -114,6 +138,27 @@ ARDUINO_DIR = /Applications/Arduino.app/Contents/Java
 
 ----
 
+### ARDUINO_PACKAGE_DIR
+
+**Description:**
+
+Directory where the Arduino package support files are stored. Can auto-detect based on default OS IDE locations.
+
+**Example:**
+
+```Makefile
+# Linux
+ARDUINO_PACKAGE_DIR = $(HOME)/.arduino15/packages
+# Mac OS X
+ARDUINO_PACKAGE_DIR = $(HOME)/Library/Arduino15/packages
+# Windows
+ARDUINO_PACKAGE_DIR = $(USERPROFILE)/AppData/Local/Arduino15/packages
+```
+
+**Requirement:** *Optional*
+
+----
+
 ### ARDUINO_PLATFORM_LIB_PATH
 
 **Description:**
@@ -155,12 +200,13 @@ ARDUINO_VERSION = 105
 
 Architecture for Arduino 1.5+
 
-Defaults to unset for 1.0 or `avr` for 1.5+
+Defaults to unset for 1.0 or `avr` for 1.5+. This value is not literally the chip architecture but will often be
+the chip series within a vendor's 'hardware' folder. For example, will default to `samd` if using Sam.mk.
 
 **Example:**
 
 ```Makefile
-ARCHITECTURE = sam
+ARCHITECTURE = arm
 ```
 
 **Requirement:** *Optional*
@@ -171,9 +217,9 @@ ARCHITECTURE = sam
 
 **Description:**
 
-Board vendor/maintainer.
+Board vendor/maintainer/series.
 
-Defaults to `arduino`
+Defaults to `arduino`.
 
 **Example:**
 
@@ -658,7 +704,8 @@ ISP_PROG = stk500v1
 
 **Description:**
 
-Device path to ArduinoISP. Not needed for hardware ISP's.
+Device path to ArduinoISP. Not needed for hardware ISP's. Also used to define
+bootloader port on SAMD devices.
 
 **Example:**
 
@@ -871,6 +918,18 @@ NM_NAME = pic32-nm
 
 ----
 
+### GDB_NAME
+
+**Description:**
+
+GDB utility.
+
+Defaults to `arm-none-eabi-gdb`
+
+**Requirement:** *Optional*
+
+----
+
 ### OPTIMIZATION_LEVEL
 
 **Description:**
@@ -1044,7 +1103,7 @@ ASFLAGS += -my-as-only-flag
 
 **Description:**
 
-Flags passed to the C pre-processor (for C, C++ and assembly source flies). Add
+Flags passed to the C pre-processor (for C, C++ and assembly source files). Add
 more flags to this variable using `+=`.
 
 Defaults to all flags required for a typical build.
@@ -1229,6 +1288,54 @@ ALTERNATE_CORE_PATH = $(HOME)/sketchbook/hardware/arduino-tiny/cores/tiny
 
 ----
 
+### CORE_VER
+
+**Description:**
+
+Alternate core release version. The Arduino board support packages are within
+a sub-directory indicated by this define.
+
+Defaults to package current release.
+
+**Example:**
+
+```Makefile
+CORE_VER = 1.6.17
+```
+
+**Requirement:** *Optional*
+
+----
+
+### CMSIS_DIR
+
+**Description:**
+
+Path to ARM CMSIS. Normally installed as part of ARM  board support.
+
+Defaults to `ARDUINO_PACKAGE_DIR/tools/CMSIS/4.5.0/CMSIS`
+
+**Example:**
+
+```Makefile
+CMSIS_DIR = /usr/share/CMSIS
+```
+
+**Requirement:** *Optional*
+
+----
+
+### CMSIS_ATMEL_DIR
+
+**Description:**
+
+Path to CMSIS-Atmel directory. Installed with ARM support package.
+
+Defaults to `ARDUINO_PACKAGE_DIR/tools/CMSIS-Atmel/1.1.0/CMSIS`
+
+**Requirement:** *Optional*
+----
+
 ### BOARDS_TXT
 
 **Description:**
@@ -1385,6 +1492,67 @@ Would result in an absolute path to the bootloader hex file of `$(HOME)/sketchbo
 
 ----
 
+### BOOTLOADER_SIZE
+
+**Description:**
+
+Size of bootloader on ARM devices, ensures correct start address when flashing
+application area. Normally parsed from boards.txt
+
+Defaults to `0x2000`
+
+**Requirement:** *Optional*
+
+----
+
+### BOOTLOADER_UNPROTECT
+
+**Description:**
+
+Bootloader unprotect sequence for upload tool. Normally parsed from boards.txt
+
+Defaults to `at91samd bootloader 0`
+
+**Requirement:** *Optional*
+
+----
+
+### BOOTLOADER_PROTECT
+
+**Description:**
+
+Bootloader protect sequence for upload tool. Normally parsed from boards.txt
+
+Defaults to `at91samd bootloader 16384`
+
+**Requirement:** *Optional*
+
+----
+
+### BOOTLOADER_PROTECT_VERIFY
+
+**Description:**
+
+Bootloader protect and verify  sequence for upload tool. Normally parsed from boards.txt
+
+Defaults to `at91samd bootloader`
+
+**Requirement:** *Optional*
+
+----
+
+### BOOTLOADER_UPLOAD_TOOL
+
+**Description:**
+
+Bootloader upload binary to use. Normally parsed from boards.txt.
+
+Defaults to `openocd`
+
+**Requirement:** *Optional*
+
+----
+
 ## ChipKIT variables
 
 ### MPIDE_DIR
@@ -1403,6 +1571,163 @@ MPIDE_DIR = $(HOME)/mpide
 
 **Requirement:** *Optional*
 
+----
+
+### MPIDE_PREFERENCES_PATH
+
+**Description:**
+
+Path to chipKIT `preferences.txt` file.
+
+Usually can be auto-detected as `AUTO_MPIDE_PREFERENCES_PATH` from the defaults `$(HOME)/.mpide/preferences.txt` (Linux) or `$(HOME)/Library/Mpide/preferences.txt` (OSX)
+
+**Example:**
+
+```Makefile
+MPIDE_PREFERENCES_PATH = $(HOME)/chipkit/preferences.txt
+```
+
+**Requirement:** *Optional*
+
+----
+
+## ARM variables
+
+### UPLOAD_TOOL
+
+**Description:**
+
+Tool to upload binary to device. Normally parsed from boards.txt.
+
+Defaults to `openocd`
+
+**Example:**
+
+```Makefile
+UPLOAD_TOOL = gdb
+```
+
+**Requirement:** *Optional*
+
+----
+
+### DEBUG
+
+**Description:**
+
+Define to set `DEBUG_FLAGS` and allow stepping of code using GDB.
+
+Defaults to undefined.
+
+**Example:**
+
+```Makefile
+DEBUG = 1
+```
+
+**Requirement:** *Optional*
+
+----
+
+### GDB_PORT
+
+**Description:**
+
+Server port to use for GDB debugging or upload. Default assumes server running
+on localhost but can re-define to use Black Magic Probe serial port.
+
+Defaults to `localhost:3333`
+
+**Example:**
+
+```Makefile
+GDB_PORT = /dev/ttyACM0
+```
+
+**Requirement:** *Optional*
+
+----
+
+### GDB_OPTS
+
+**Description:**
+
+Optional arguments to parse to GDB command.
+
+Defaults to `-ex "target extended-remote $(GDB_PORT)" -ex "monitor swdp_scan" -ex "attach 1" -ex "load" -d $(OBJDIR) $(TARGET_ELF)`
+
+**Requirement:** *Optional*
+
+----
+
+### GDB_UPLOAD_OPTS
+
+**Description:**
+
+Optional arguments to parse to GDB command when uploading binary only.
+
+Defaults to `GDB_UPLOAD_OPTS = $(GDB_OPTS) -ex "set confirm off" -ex "set target-async off" -ex "set remotetimeout 30" -ex "detach" -ex "kill" -ex "quit"`
+
+**Requirement:** *Optional*
+
+----
+
+### BOSSA
+
+**Description:**
+
+Path to bossac binary.
+
+Can usually be detected from `$ARDUINO_PACKAGE_DIR` /tools subdirectory when ARM
+device support is installed.
+
+**Requirement:** *Optional*
+
+----
+
+### BOSSA_OPTS
+
+**Description:**
+
+Flags to pass to bossac command.
+
+Defaults to `-d --info --erase --write --verify --reset`
+
+**Requirement:** *Optional*
+
+----
+
+### OPENOCD
+
+**Description:**
+
+Path to openocd binary.
+
+Can usually be detected from `$ARDUINO_PACKAGE_DIR` /tools subdirectory when ARM
+device support is installed.
+
+**Requirement:** *Optional*
+
+----
+
+### OPENOCD_OPTS
+
+**Description:**
+
+Flags to pass to openocd command. If using openocd from non-Arduino
+distributions, one should define this with the path to the Arduino openocd script.
+
+Defaults to `-d2`
+
+Example:
+
+```Makefile
+OPENOCD_OPTS = $(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/tools/openocd/0.9.0-arduino6-static/share/openocd/scripts/ -f $(ARDUINO_PACKAGE_DIR)/$(ARDMK_VENDOR)/hardware/samd/1.6.17/variants/$(VARIANT)/$(OPENOCD_SCRIPT) 
+```
+
+**Requirement:** *Optional*
+
+
 ----
 
 ## Ctags variables
@@ -1453,21 +1778,3 @@ CTAGS_CMD = /usr/local/bin/
 ```
 
 **Requirement:** *Optional*
-
-----
-
-### MPIDE_PREFERENCES_PATH
-
-**Description:**
-
-Path to chipKIT `preferences.txt` file.
-
-Usually can be auto-detected as `AUTO_MPIDE_PREFERENCES_PATH` from the defaults `$(HOME)/.mpide/preferences.txt` (Linux) or `$(HOME)/Library/Mpide/preferences.txt` (OSX)
-
-**Example:**
-
-```Makefile
-MPIDE_PREFERENCES_PATH = $(HOME)/chipkit/preferences.txt
-```
-
-**Requirement:** *Optional*
diff --git a/bin/ard-reset-arduino b/bin/ard-reset-arduino
index 1f2c7e9..d6f974f 100755
--- a/bin/ard-reset-arduino
+++ b/bin/ard-reset-arduino
@@ -2,6 +2,7 @@
 
 from __future__ import print_function
 import serial
+import serial.tools.list_ports
 import os.path
 import argparse
 from time import sleep
@@ -13,13 +14,100 @@ except:
   pyserial_version = 2  # less than 2.3
 
 parser = argparse.ArgumentParser(description='Reset an Arduino')
+parser.add_argument('--zero', action='store_true', help='Reset Arduino Zero or similar Native USB to enter bootloader')
 parser.add_argument('--caterina', action='store_true', help='Reset a Leonardo, Micro, Robot or LilyPadUSB.')
 parser.add_argument('--verbose', action='store_true', help="Watch what's going on on STDERR.")
 parser.add_argument('--period', default=0.1, help='Specify the DTR pulse width in seconds.')
 parser.add_argument('port', nargs=1, help='Serial device e.g. /dev/ttyACM0')
 args = parser.parse_args()
 
-if args.caterina:
+
+def list_ports(output=False):
+    """ Lists serial ports attached
+
+        :returns
+            A list of paths to serial ports on system
+    """
+    ports = serial.tools.list_ports.comports()
+    connected = [port[0] for port in ports]
+    if output:
+        print(connected)
+
+    return connected
+
+
+def new_port(old, new):
+    """ Checks if a new port has attached
+
+        Args:
+            old: previous list of ports to check
+            new: current list of ports to check
+        Returns:
+            index of port in 'new' if new port found, otherwise -1
+    """
+    new_port = -1
+
+    for port in new:
+        if port not in old:
+            new_port = new.index(port)
+            break
+
+    return new_port
+
+
+if args.zero:
+    # number of trys to attempt
+    zero_attempts = 20 # ~2 seconds
+    initial_ports = list_ports(args.verbose)
+
+    if args.verbose:
+        print('Attempting to enter bootloader using 1200 bps open/close on port %s' % args.port[0])
+
+    ser = serial.Serial(args.port[0], 57600)
+    ser.close()
+
+    if pyserial_version < 3:
+        ser.setBaudrate(1200)
+    else:
+        ser.baudrate = 1200
+
+    # do the open/close at 1200 BAUD
+    ser.open()
+    ser.close()
+
+    if args.verbose:
+        print('Done. Waiting for bootloader port to attach...')
+
+    # get new list of ports
+    reset_ports = list_ports(args.verbose)
+
+    # wait for new port or port to return
+    port_index = new_port(initial_ports, reset_ports)
+
+    # keep checking until new port appears or timeout
+    while port_index < 0:
+        # count down attempts and leave if expired
+        zero_attempts -= 1
+        if zero_attempts < 0:
+            break
+        sleep(0.1)
+        # get list of ports after bootloader toggle performed
+        reset_ports = list_ports(args.verbose)
+        # if a port drops, set initial ports to reset ports so that
+        # next attached device will be new port
+        if (len(reset_ports) < len(initial_ports)):
+            initial_ports = reset_ports
+        # check if a new port has attached and return the index if it has
+        port_index = new_port(initial_ports, reset_ports)
+    # return the new port if detected, otherwise return passed port
+    if port_index is -1:
+        bootloader_port = args.port[0]
+    else:
+        bootloader_port = reset_ports[port_index]
+
+    # print so that `tail -1` can be piped for bootloader port
+    print(bootloader_port)
+elif args.caterina:
     if args.verbose: print('Forcing reset using 1200bps open/close on port %s' % args.port[0])
     ser = serial.Serial(args.port[0], 57600)
     ser.close()
diff --git a/examples/MZeroBlink/MZeroBlink.ino b/examples/MZeroBlink/MZeroBlink.ino
new file mode 100644
index 0000000..f9a59a9
--- /dev/null
+++ b/examples/MZeroBlink/MZeroBlink.ino
@@ -0,0 +1,19 @@
+/*
+  Blink
+  Turns on an LED on for one second, then off for one second, repeatedly.
+
+  This example code is in the public domain.
+ */
+
+void setup() {
+  // initialize the digital pin as an output.
+  // Pin 13 has an LED connected on most Arduino boards:
+  pinMode(13, OUTPUT);
+}
+
+void loop() {
+  digitalWrite(13, HIGH);   // set the LED on
+  delay(1000);              // wait for a second
+  digitalWrite(13, LOW);    // set the LED off
+  delay(1000);              // wait for a second
+}
diff --git a/examples/MZeroBlink/Makefile b/examples/MZeroBlink/Makefile
new file mode 100644
index 0000000..29cb90b
--- /dev/null
+++ b/examples/MZeroBlink/Makefile
@@ -0,0 +1,24 @@
+# Arduino M0 Pro Programming Port
+BOARD_TAG = mzero_pro_bl_dbg
+
+# Define debug if you want to use gdb
+#DEBUG = 1
+
+# Define port if using Black Magic Probe rather than default localhost:3333
+#GDB_PORT = /dev/ttyACM0
+
+# Define ARM toolchain dir if not using Arduino supplied
+#ARM_TOOLS_DIR = /usr
+
+# Define AVR toolchain dir if not using Arduino supplied and using native port
+#AVR_TOOLS_DIR = /usr
+
+# Define Arduino support package installation path where SAM device support has been installed
+# Linux
+# ARDUINO_PACKAGE_DIR := $(HOME)/.arduino15/packages
+# macOS
+# ARDUINO_PACKAGE_DIR := $(HOME)/Library/Arduino15/packages
+# Windows
+# ARDUINO_PACKAGE_DIR := "C:/Users/$(USER)/AppData/Local/Arduino15/packages"
+
+include ../../Sam.mk
diff --git a/examples/ZeroBlink/Makefile b/examples/ZeroBlink/Makefile
new file mode 100644
index 0000000..60c8435
--- /dev/null
+++ b/examples/ZeroBlink/Makefile
@@ -0,0 +1,30 @@
+# Arduino Zero Native Port (should work with Feather, MKR1000 etc.)
+# BOOTLOADER: The bootloader on these devices loaded when reset is pressed twice
+# or the port is opened/closed at 1200 BAUD. If there is no program on the device,
+# you may have to manually enter bootloader by toggling reset twice.
+# see http://www.avdweb.nl/arduino/samd21/virus.html
+BOARD_TAG = arduino_zero_native
+
+# Define alternative core path if using another board supplier
+#ALTERNATE_CORE_PATH = $(HOME)/Arduino/hardware/sparkfun/samd
+
+# Define monitor port and isp port (bootloader port).
+# Will automatically detect if Linux/macOS but MUST be defined on Windows
+#MONITOR_PORT = com40 # CDC serial
+#ISP_PORT = com39 # bootloader
+
+# Define ARM toolchain dir if not using Arduino supplied
+#ARM_TOOLS_DIR = /usr
+
+# Define AVR toolchain dir if not using Arduino supplied and using native port
+#AVR_TOOLS_DIR = /usr
+
+# Define Arduino support package installation path where SAM device support has been installed
+# Linux
+#ARDUINO_PACKAGE_DIR := $(HOME)/.arduino15/packages
+# macOS
+#ARDUINO_PACKAGE_DIR := $(HOME)/Library/Arduino15/packages
+# Windows
+#ARDUINO_PACKAGE_DIR := "C:/Users/$(USER)/AppData/Local/Arduino15/packages"
+
+include ../../Sam.mk
diff --git a/examples/ZeroBlink/ZeroBlink.ino b/examples/ZeroBlink/ZeroBlink.ino
new file mode 100644
index 0000000..f9a59a9
--- /dev/null
+++ b/examples/ZeroBlink/ZeroBlink.ino
@@ -0,0 +1,19 @@
+/*
+  Blink
+  Turns on an LED on for one second, then off for one second, repeatedly.
+
+  This example code is in the public domain.
+ */
+
+void setup() {
+  // initialize the digital pin as an output.
+  // Pin 13 has an LED connected on most Arduino boards:
+  pinMode(13, OUTPUT);
+}
+
+void loop() {
+  digitalWrite(13, HIGH);   // set the LED on
+  delay(1000);              // wait for a second
+  digitalWrite(13, LOW);    // set the LED off
+  delay(1000);              // wait for a second
+}
diff --git a/tests/script/runtests.sh b/tests/script/runtests.sh
index 7792186..648a0cf 100755
--- a/tests/script/runtests.sh
+++ b/tests/script/runtests.sh
@@ -7,7 +7,7 @@ failures=()
 # These examples cannot be tested easily at the moment as they require
 # alternate cores. The MakefileExample doesn't actually contain any source code
 # to compile.
-NON_TESTABLE_EXAMPLES=(ATtinyBlink MakefileExample TinySoftWareSerial BlinkOpenCM BlinkTeensy BlinkNetworkRPi BlinkInAVRC)
+NON_TESTABLE_EXAMPLES=(ATtinyBlink MakefileExample TinySoftWareSerial BlinkOpenCM BlinkTeensy BlinkNetworkRPi BlinkInAVRC MZeroBlink ZeroBlink)
 
 for dir in $TESTS_DIR/*/
 do